Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.24 (mitogen-activated protein kinase)
 95,810 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The purpose of the present study was to elucidate the possible signal transduction pathway involved in the underlying mechanism of glucosamine (GLN)'s influence on the gene expression of matrix metalloproteinases (MMPs) in chondrocytes stimulated with IL-1beta. Using chondrosarcoma cells stimulated with IL-1beta, the effects of GLN on the mRNA and protein levels of MMP-3, the activation of JNK, ERK, p38, NF-kappaB, and AP-1, the nuclear translocation of NF-kappaB/Rel family members, and PI3-kinase/Akt activation were studied. GLN inhibited the expression and the synthesis of MMP-3 induced by IL-1beta, and that inhibition was mediated at the level of transcription involving both the NF-kappaB and AP-1 transcription factors. Translocation of NF-kappaB was reduced by GLN as a result of the inhibition of IkappaB degradation. A slightly synergistic effect on the activation of AP-1 induced by IL-1beta was shown in the presence of GLN. Among MAPK pathways involved in the transcriptional regulation of AP-1, phosphorylation of JNK and ERK was found to increase with the presence of GLN under IL-1beta treatment, while that for p38 decreased. It was also found that GLN alone, but also synergistically with IL-1beta, was able to activate the Akt pathway. The requirements of NF-kappaB translocation and p38 activity are indispensably involved in the induction of MMP-3 expression in chondrosarcoma cells stimulated by IL-1beta. Inhibition of the p38 pathway in the presence of GLN substantially explains the chondroprotective effect of GLN on chondrocytes that regulate COX-2 expression, PGE(2) synthesis, and NO expression and synthesis. The chondroprotective effect of GLN through the decrease in MMP-3 production and stimulation of proteoglycan synthesis may follow another potential signaling pathway of Akt.
 ...
PMID:Chondroprotective effects of glucosamine involving the p38 MAPK and Akt signaling pathways. 1834 Apr 49

Both CCN family 2/connective tissue growth factor (CCN2/CTGF) and bone morphogenetic protein (BMP)-2 play an important role in cartilage metabolism. We evaluated whether or not CCN2 would interact with BMP-2, and examined the combination effect of CCN2 with BMP-2 (CCN2-BMP-2) on the proliferation and differentiation of chondrocytes. Immunoprecipitation-western blotting analysis, solid-phase binding assay and surface plasmon resonance (SPR) spectroscopy showed that CCN2 directly interacted with BMP-2 with a dissociation constant of 0.77 nM as evaluated by SPR. An in vivo study revealed that CCN2 was co-localized with BMP-2 at the pre-hypertrophic region in the E18.5 mouse growth plate. Interestingly, CCN2-BMP-2 did not affect the BMP-2/CCN2-induced phosphorylation of p38 MAPK but caused less phosphorylation of ERK1/2 in cultured chondrocytes. Consistent with these results, cell proliferation assay showed that CCN2-BMP-2 stimulated cell growth to a lesser degree than by either CCN2 or BMP-2 alone, whereas the expression of chondrocyte marker genes and proteoglycan synthesis, representing the mature chondrocytic phenotype, was increased collaboratively by CCN2-BMP-2 treatment in cultured chondrocytes. These findings suggest that CCN2 may regulate the proliferating and differentiation of chondrocytes by forming a complex with BMP-2 as a novel modulator of BMP signalling.
 ...
PMID:CCN family 2/connective tissue growth factor modulates BMP signalling as a signal conductor, which action regulates the proliferation and differentiation of chondrocytes. 2176 22

Versican/PG-M is a large chondroitin sulfate proteoglycan of the extracellular matrix which interacts with hyaluronan at the N-terminal G1 domain, composed of A, B, and B' subdomains. Recently, we generated knock-in mice Cspg2(Delta3/Delta3), whose versican, without the A subdomain, has decreased hyaluronan (HA) binding affinity, thereby exhibiting reduced deposition of versican in the extracellular matrix. Here, we show that the Cspg2(Delta3/Delta3) fibroblasts within 20 passages proliferate more slowly and acquire senescence. Whereas the extracellular matrix of the wild type fibroblasts exhibited a network structure of hyaluronan and versican, that of the Cspg2(Delta3/Delta3) fibroblasts exhibited approximately 35 and approximately 85% deposition of versican and HA, without such a structure. The Cspg2(Delta3/Delta3) fibroblasts showed a substantial increase of ERK1/2 phosphorylation and expression of senescence markers p53, p21, and p16. Treatment of wild type fibroblasts with hyaluronidase and exogenous hyaluronan enhanced ERK1/2 phosphorylation, and treatment with an anti-CD44 antibody that blocks HA-CD44 interaction inhibited the phosphorylation. These results demonstrate that versican is essential for matrix assembly involving hyaluronan and that diminished versican deposition increases free hyaluronan fragments that interact with CD44 and increase phosphorylation of ERK1/2, leading to cellular senescence.
 ...
PMID:Versican/PG-M Assembles Hyaluronan into Extracellular Matrix and Inhibits CD44-mediated Signaling toward Premature Senescence in Embryonic Fibroblasts. 1916 94

In fibroblast growth factor (FGF)-2 signaling, the formation of a ternary complex of FGF-2, tyrosine-kinase fibroblast growth factor receptor (FGFR)-1, and cell surface heparan sulfate (HS) proteoglycan is known to be critical for the activation of FGFR-1 and downstream signal transduction. Exogenous heparin polymer and some octasaccharides inhibited FGF-2-induced phosphorylation both of FGFR-1 and of extracellular signal-regulated kinase (ERK1/2) in Chinese hamster ovary (CHO)-K1 cells transfected with FGFR-1, which present HS on their cell surface. The inhibitory effect of octasaccharide was dependent on the number of 2-O-sulfate groups within a molecule but independent of the number of 6-O-sulfate groups. Sulfation at the 2-O-position was a prerequisite not only for the binding of HS to FGF-2 but also for regulation of FGF-2 signaling and competitive inhibition with endogenous HS. Interestingly, FGF-4-induced phosphorylation was impeded only by specific octasaccharides containing both 2-O- and 6-O-sulfated groups, which were necessary for binding FGF-4. In CHO-677 cells deficient in HS biosynthesis, heparin enhanced FGF-2-induced phosphorylation of ERK1/2. On the other hand, an FGF-2-binding octasaccharide inhibited the phosphorylation. Our data suggest that the activity of particular heparin-binding factors can be inhibited by distinctive oligosaccharides that can bind the factors but cannot form functional signaling complexes irrespective of whether cells have a normal complement of HS or lack HS.
 ...
PMID:Specific inhibition of FGF-2 signaling with 2-O-sulfated octasaccharides of heparan sulfate. 1925 61

Over production of collagen and its abnormal assembly is the hallmark of abnormal scars such as keloids, a condition which reflects fibrosis of the skin. Fibrotic conditions of organs such as liver, lungs and eyes are characterized by low levels of decorin, a member of the small leucine proteoglycan family, which is an indispensable modulator of collagen assembly. Involvement of decorin in keloids is not well described, therefore, its expression in keloids was studied here. We showed low decorin levels in the total tissue extract of keloids as compared to normal skin. Further, we showed that this low level is due to reduced transcription of decorin by keloid fibroblasts. As decorin can also act as an intermediate signaling molecule involved in the ERK1,2 pathway, levels of both ERK1,2 and its activated counterpart were studied and found to be up-regulated in keloids. Through this study a novel attempt has been made to understand the implications of decorin expression and a possible cause of over production of collagen and its aberrant assembly in keloids is suggested.
 ...
PMID:Low decorin expression along with inherent activation of ERK1,2 in ear lobe keloids. 1926 70

Versican is a large chondroitin sulfate proteoglycan of the extracellular matrix that is involved in a variety of cellular processes. We showed previously that versican, which is overexpressed in cutaneous melanomas as well as in premalignant lesions, contributes to melanoma progression, favoring the detachment of cells and the metastatic dissemination. Here, we investigated the transcriptional regulation of the versican promoter in melanoma cell lines with different levels of biological aggressiveness and stages of differentiation. We show that versican promoter up-regulation accounts for the differential expression levels of mRNA and protein detected in the invasive SK-mel-131 human melanoma cells. The activity of the versican promoter increased 5-fold in these cells in comparison with that measured in non-invasive MeWo melanoma cells. Several transcriptional regulatory elements were identified in the proximal promoter, including AP-1, Sp1, AP-2, and two TCF-4 sites. We show that promoter activation is mediated by the ERK/MAPK and JNK signaling pathways acting on the AP-1 site, suggesting that BRAF mutation present in SK-mel-131 cells impinge upon the up-regulation of the versican gene through signaling elicited by the ERK/MAPK pathway. This is the first time the AP-1 transcription factor family has been shown to be related to the regulation of versican expression. Furthermore, deletion of the TCF-4 binding sites caused a 60% decrease in the promoter activity in SK-mel-131 cells. These results showing that AP-1 and TCF-4 binding sites are the main regulatory regions directing versican production provide new insights into versican promoter regulation during melanoma progression.
 ...
PMID:Structure and regulation of the versican promoter: the versican promoter is regulated by AP-1 and TCF transcription factors in invasive human melanoma cells. 1926 71

Multiple inflammatory mediators in osteoarthritis (OA) cartilage, including S100/calgranulin ligands of receptor for advanced glycation end products (RAGE), promote chondrocyte hypertrophy, a differentiation state associated with matrix catabolism. In this study, we observed that RAGE knockout was not chondroprotective in instability-induced knee OA in 8-wk-old mice. Hence, we tested the hypothesis that expression of the alternative S100/calgranulin and patterning receptor CD36, identified here as a marker of growth plate chondrocyte hypertrophy, mediates chondrocyte inflammatory and differentiation responses that promote OA. In rat knee joint destabilization-induced OA, RAGE expression was initially sparse throughout cartilage but increased diffusely by 4 wk after surgery. In contrast, CD36 expression focally increased at sites of cartilage injury and colocalized with developing chondrocyte hypertrophy and aggrecan cleavage NITEGE neoepitope formation. However, CD36 transfection in normal human knee-immortalized chondrocytes (CH-8 cells) was associated with decreased capacity of S100A11 and TNF-alpha to induce chondrocyte hypertrophy and ADAMTS-4 and matrix metalloproteinase 13 expression. S100A11 lost the capacity to inhibit proteoglycans synthesis and gained the capacity to induce proteoglycan synthesis in CD36-transfected CH-8 cells. Moreover, S100A11 required the p38 MAPK pathway kinase MKK3 to induce NITEGE development in mouse articular cartilage explants. However, CH-8 cells transfected with CD36 demonstrated decreased S100A11-induced MKK3 and p38 phosphorylation. Therefore, RAGE and CD36 patterning receptor expression were linked with opposing effects on inflammatory, procatabolic responses to S100A11 and TNF-alpha in chondrocytes.
 ...
PMID:The pattern recognition receptor CD36 is a chondrocyte hypertrophy marker associated with suppression of catabolic responses and promotion of repair responses to inflammatory stimuli. 1934 82

In a screening program aimed at discovering anti-osteoarthritis (OA) drugs, we identified an imidazo[5,1-c][1,4]thiazine derivative, ITZ-1, that suppressed both interleukin-1beta (IL-1beta)-induced proteoglycan and collagen release from bovine nasal cartilage in vitro and suppressed intra-articular infusion of IL-1beta-induced cartilage proteoglycan degradation in rat knee joints. ITZ-1 did not inhibit enzyme activities of various matrix metalloproteinases (MMPs), which have pivotal roles in cartilage degradation, while it selectively inhibited IL-1beta-induced production of MMP-13 in human articular chondrocytes (HAC). IL-1beta-induced MMP production has been shown to be mediated by extracellular signal-regulated protein kinase (ERK), p38 kinase, and c-Jun N-terminal kinase (JNK) of the mitogen-activated protein kinase (MAPK) family signal transduction molecules. An ERK-MAPK pathway inhibitor (U0126), but not a p38 kinase inhibitor (SB203580) or a JNK inhibitor (SP600125), also selectively inhibited IL-1beta-induced MMP-13 production in HAC. Furthermore, ITZ-1 selectively inhibited IL-1beta-induced ERK activation without affecting p38 kinase and JNK activation, which may account for its selective inhibition of MMP-13 production. Inhibition of nitric oxide (NO)-induced chondrocyte apoptosis has been another area of interest as a therapeutic strategy for OA, and ITZ-1 also suppressed NO-induced death in HAC. These results suggest that ITZ-1 is a promising lead compound for a disease modifying anti-OA drug program.
 ...
PMID:The chondroprotective agent ITZ-1 inhibits interleukin-1beta-induced matrix metalloproteinase-13 production and suppresses nitric oxide-induced chondrocyte death. 1954 81

Aggrecan cleavage by a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 5 (ADAMTS-5) is crucial for the breakdown of cartilage matrix during osteoarthritis, a degenerative joint disease that leads to the progressive destruction of articular structures. The mechanisms of ADAMTS-5 activation and their links to the pathogenesis of osteoarthritis remain poorly understood, but syndecans have been shown to be involved in the activation of ADAMTS-4 (ref. 3). Here we show that syndecan-4 is specifically induced in type X collagen-producing chondrocytes both in human osteoarthritis and in murine models of the disease. The loss of syndecan-4 in genetically modified mice and intra-articular injections of syndecan-4-specific antibodies into wild-type mice protect from proteoglycan loss and thereby prevent osteoarthritic cartilage damage in a surgically induced model of osteoarthritis. The occurrence of less severe osteoarthritis-like cartilage destruction in both syndecan-4-deficient mice and syndecan-4-specific antibody-treated wild-type mice results from a marked decrease in ADAMTS-5 activity. Syndecan-4 controls the activation of ADAMTS-5 through direct interaction with the protease and through regulating mitogen-activated protein kinase (MAPK)-dependent synthesis of matrix metalloproteinase-3 (MMP-3). Our data suggest that strategies aimed at the inhibition of syndecan-4 will be of great value for the treatment of cartilage damage in osteoarthritis.
 ...
PMID:Syndecan-4 regulates ADAMTS-5 activation and cartilage breakdown in osteoarthritis. 1968 82

Fibrosis is the response of heart and other organs to injuries. Excessive fibrosis can cause organ dysfunction or even failure. Transforming-growth factor (TGF)-beta is a cytokine that induces fibroblast proliferation and increases the synthesis of a number of extracellular matrix proteins including collagens. Decorin (DCN) is a natural antagonist of TGF-beta. In the current study, we investigated the potential antifibrotic effects of DCN gene delivery by a recombinant adeno-associated viral (rAAV) vector to inhibit cardiac fibrosis in old, spontaneously hypertensive rats (SHRs), which develop severe cardiac and kidney fibrosis if without intervention. The rAAV-DCN vector was injected (at a dose of 1 x 10(11) vector genomes) via the tail vein into 5-month-old male SHRs, resulting in persistent, stable expression of DCN (up to 16 weeks). rAAV-DCN treatment significantly reduced collagen content and fibrosis in the heart and attenuated cardiomyocyte hypertrophy. Hemodynamics data at 16 weeks showed that DCN gene delivery induced a significant increase in left ventricular end-systolic pressure and maximal-minimal rate of pressure increase (+/-dp/dt(max)), but a decrease in left ventricular end-diastolic pressure (p < 0.05), compared with those of control animals. The expression of TGF-beta and alpha-smooth muscle actin, and the phosphorylation levels of Smad2 and p38 MAPK, were markedly reduced by rAAV-DCN treatment as compared with the controls. Thus, these results suggest that rAAV-mediated DCN overexpression led to the inhibition of hypertension-induced cardiac fibrosis and hypertrophy and improved cardiac function, and therefore may have therapeutic potential for organ fibrosis.
 ...
PMID:Decorin gene delivery inhibits cardiac fibrosis in spontaneously hypertensive rats by modulation of transforming growth factor-beta/Smad and p38 mitogen-activated protein kinase signaling pathways. 1969 98


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>